Field of Invention
Various embodiments of the present disclosure relate to a network access method, and more particularly, to a network access method and apparatus for supporting mobility of user equipment.
Description of Related Art
Today's Internet has a severe scalability problem regarding routing and addressing. The scalability problem may occur due to multihoming, traffic engineering, and nonaggregatable address allocation. Due to such a scalability problem, there occurs a phenomenon where the size of a routing table in a default route free zone increases geometrically.
The multihoming which is the reason behind the increase of routing table entries refers to a site having multi-path for accessing the Internet, thereby guaranteeing one or more paths for accessing the Internet to use in case a problem occurs. This is because an address block allocated to a site that is connected to the Internet through a plurality of ISPs (Internet Service Providers) must be stored in different ISP routing tables. The traffic engineering which is another reason behind the increase of routing table entries may have a path to a destination that is different from the shortest path on the topology, and thus each piece of path information must be individually stored in the routing table, thereby causing the problem of scalability. The nonaggregatable address allocation which is another reason behind the increase of routing table entries causes the problem of scalability since topological aggregation is the only method for controlling the increase of routing table entries. Due to these reasons, the size of routing tables in an Internet default route free zone is increasing rapidly, and thus the performance of a router may soon reach its limitations.
The IETF (Internet Engineering Task Force) held an ROAP (Routing and Addressing Problem) BoF (Birds of a Feather) conference in an IETF conference in order to resolve the scalability problem of routing and addressing. A method determined in this conference was to design a new Internet architecture, a structure of separating an identifier and a locator.
The current IP (Internet Protocol) addresses use both the meaning of an identifier and a locator of an end host, and thus when a host in communication moves, the IP address of the host changes. Such a change of an IP address means a change in both the identifier and the locator of a host in communication, that is, a session in communication being disconnected, making it difficult to perform a continuous seamless service. The same goes with multihoming trying to resume communication through another link when a problem occurs during communication. Therefore, considering the mobility and multihoming of a mobile host, the location of the mobile host must be dynamically changed for routing to the exact current location, whereas the identifier of the mobile host must not be changed but maintain the session in communication for a sustainable service. Therefore, to provide mobility and multihoming of the host, the identifier and the location of the host must be separated from each other.